US4577594A - Cooling system for automotive engine - Google Patents

Cooling system for automotive engine Download PDF

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Publication number
US4577594A
US4577594A US06/704,269 US70426985A US4577594A US 4577594 A US4577594 A US 4577594A US 70426985 A US70426985 A US 70426985A US 4577594 A US4577594 A US 4577594A
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United States
Prior art keywords
coolant
level
cooling circuit
engine
radiator
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US06/704,269
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English (en)
Inventor
Yoshimasa Hayashi
Takao Kubozuka
Yoshinori Hirano
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Nissan Motor Co Ltd
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Nissan Motor Co Ltd
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Publication date
Priority claimed from JP3299484A external-priority patent/JPS60175727A/ja
Priority claimed from JP10015584A external-priority patent/JPS60243320A/ja
Priority claimed from JP10015784A external-priority patent/JPS60243318A/ja
Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Assigned to NISSAN MOTOR CO., LTD reassignment NISSAN MOTOR CO., LTD ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HAYASHI, YOSHIMASA, HIRANO, YOSHINORI, KUBOZUKA, TAKAO
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P11/00—Component parts, details, or accessories not provided for in, or of interest apart from, groups F01P1/00 - F01P9/00
    • F01P11/02—Liquid-coolant filling, overflow, venting, or draining devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/22—Liquid cooling characterised by evaporation and condensation of coolant in closed cycles; characterised by the coolant reaching higher temperatures than normal atmospheric boiling-point
    • F01P3/2285—Closed cycles with condenser and feed pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control

Definitions

  • the present invention relates generally to a cooling system for an internal combustion engine wherein liquid coolant is boiled to make use of the latent heat of vaporization of the same and the vapor used as a vehicle for removing heat from the engine, and more specifically to such a system which includes a control arrangement which monitors and controls the amount of coolant retained in the cooling circuit under all modes of operation.
  • FIG. 2 shows an arrangement disclosed in Japanese Patent Application Second Provisional Publication No. Sho 57-57608. This arrangement has attempted to vaporize a liquid coolant and use the gaseous form thereof as a vehicle for removing heat from the engine.
  • the radiator 1 and the coolant jacket 2 are in constant and free communication via conduits 3, 4 whereby the coolant which condenses in the radiator 1 is returned to the coolant jacket 2 little by little under the influence of gravity.
  • a gas permeable water shedding filter 5 is arranged as shown, to permit the entry of air into and out of the system.
  • this filter permits gaseous coolant to gradually escape from the system, inducing the need for frequent topping up of the coolant level.
  • a further problem with this arrangement has come in that some of the air, which is sucked into the cooling system as the engine cools, tends to dissolve in the water, whereby upon start up of the engine, the dissolved air tends to form small bubbles in the radiator which adhere to the walls thereof forming an insulating layer. The undissolved air tends to collect in the upper section of the radiator and inhibit the convection-like circulation of the vapor from the cylinder block to the radiator. This of course further deteriorates the performance of the device.
  • European Patent Application Provisional Publication No. 0 059 423 published on Sept. 8, 1982 discloses another arrangement wherein, liquid coolant in the coolant jackets of the engine, is not circulated therein and permitted to absorb heat to the point of boiling.
  • the gaseous coolant thus generated is adiabatically compressed in a compressor so as to raise the temperature and pressure thereof and introduced into a heat exchanger. After condensing, the coolant is temporarily stored in a reservoir and recycled back into the coolant jacket via a flow control valve.
  • U.S. Pat. No. 4,367,699 issued on Jan. 11, 1983 in the name of Evans discloses an engine system wherein the coolant is boiled and the vapor used to remove heat from the engine.
  • This arrangement features a separation tank 6 wherein gaseous and liquid coolant are initially separated.
  • the liquid coolant is fed back to the cylinder block 7 under the influence of gravity while the "dry" gaseous coolant (steam for example) is condensed in a fan cooled radiator 8.
  • the temperature of the radiator is controlled by selective energizations of the fan 9 to maintain a rate of condensation therein sufficient to sustain a liquid seal at the bottom of the device.
  • Condensate discharged from the radiator via the above mentioned liquid seal is collected in a small reservoir-like arrangement 10 and pumped back up to the separation tank via a small pump 11.
  • This arrangement while providing an arrangement via which air can be initially purged from the system tends to, due to the nature of the arrangement which permits said initial non-condensible matter to be forced out of the system, suffers from rapid loss of coolant when operated at relatively high altitudes. Further, once the engine cools air is relatively freely admitted back into the system. The provision of the separation tank 6 also renders engine layout difficult.
  • Japanese Patent Application First Provisional Publication No. Sho. 56-32026 discloses an arrangement wherein the structure defining the cylinder head and cylinder liners are covered in a porous layer of ceramic material 12 and coolant sprayed into the cylinder block from shower-like arrangements 13 located above the cylinder heads 14.
  • the interior of the coolant jacket defined within the engine proper is essentially filled with gaseous coolant during engine operation during which liquid coolant sprayed onto the ceramic layers 12.
  • this arrangement has proved totally unsatisfactory in that upon boiling of the liquid coolant absorbed into the ceramic layers the vapor thus produced escaping into the coolant jacket inhibits the penetration of liquid coolant into the layers whereby rapid overheat and thermal damage of the ceramic layers 12 and/or engine soon results. Further, this arrangement is plagued with air contamination and blockages in the radiator similar to the compressor equipped arrangement discussed above.
  • This pump is disposed in a small reservoir located at the bottom of the radiator or condensor in which the coolant vapor is condensed.
  • a valve is arranged to vent the reservoir with the ambient atmosphere and thus maintain the interior of the radiator and coolant jacket at ambient atmospheric pressure under all operating conditions.
  • a cooling circuit cooling jacket, radiator and condensate return arrangemement
  • Another object of the present invention is to provide a system of the nature indicated above wherein the boiling point of the engine coolant can be controlled in response to changes in engine operation.
  • a vapor cooled type internal combustion engine which is provided with an auxiliary reservoir and a coolant management system.
  • the management system establishes fluid communication between the reservoir and a cooling circuit of the engine in a manner to fill the latter with liquid coolant when the engine is not in use and thus exclude contaminating non-condensible air from same, and monitors the operation of the system when operating in a closed mode to determine if too much or too little coolant has been retained in the circuit following a warm-up mode wherein the excess coolant which fills the system when cold, is displaced by its own vapor pressure.
  • the management system also ensures that the cooling circuit is not switched from closed to open states until predetermined temperature and pressure requirements are both met, and thus prevents violent displacement of coolant out of the circuit to the reservoir in a manner which invites spillage of coolant and the entry of large amounts of contaminating air.
  • control circuit including a microprocessor (or the like) which is arranged to selectively induce:
  • a retained coolant check/control mode wherein data derived by monitoring the temperature of the coolant, the operation of a coolant return pump and the outputs of level sensors disposed in the coolant jacket and at the bottom of the radiator, the presence of excess coolant and/or the lack of thereof within the system when conditioned to assume a closed condition, is determined and the appropriate correction undertaken;
  • a system shut-down mode wherein the coolant temperature and pressure within the system are quickly reduced by briefly continuing the use of a cooling device (e.g. fan) until both the temperature and pressure in the "cooling circuit" to levels which eliminates any positive pressure which tends to displace overly large amounts of coolant out of the system to an externally disposed coolant reservoir, upon the system being switched from a closed state to an open one.
  • a cooling device e.g. fan
  • a first aspect of the present invention takes the form of a cooling system for an internal combustion engine which system comprises: a coolant jacket formed about structure of the engine subject to high heat flux; a radiator in which coolant vapor is condensed to its liquid form; a vapor transfer conduit leading from the coolant jacket to the radiator; means for returning liquid coolant from the radiator to the coolant jacket in a manner to maintain the structure subject to high heat flux immersed in liquid coolant and define a vapor collection space within the coolant jacket; a reservoir containing liquid coolant; valve and conduit means for selectively establishing fluid communication between the coolant jacket and the reservoir; and valve and conduit control means including circuitry for: (a) conditioning the valve and conduit means so as to establish fluid communication between the reservoir and a cooling circuit which includes the coolant jacket, the radiator and the second vapor transfer conduit, when the temperature of the coolant within the coolant jacket is below a first predetermined level and the pressure prevailing within the cooling circuit is below ambient atmospheric pressure by second predetermind value; (b) conditioning the valve and
  • a second aspect of the invention takes the form of a method of cooling an internal combustion engine which comprises the steps of: introducing liquid coolant into a coolant jacket formed about structure of the engine subject to high heat flux in a manner to immerse the structure in a predetermined depth of liquid coolant; allowing the liquid coolant in the coolant jacket to boil; condensing the vapor produced by the boiling in the coolant jacket to its liquid form in a radiator; transferring the coolant vapor from the coolant jacket to the radiator using a vapor transfer conduit; returning liquid coolant from the radiator to the first coolant jacket using a coolant return arrangement in a manner to maintain the structure subject to high heat flux immersed in the predetermined depth of liquid coolant and define a vapor collection space within the coolant jacket; storing additional coolant in a reservoir; conditioning the valve and conduit means so as to establish fluid communication between the reservoir and a cooling circuit which includes the coolant jacket, the radiator and the second vapor transfer conduit, when the temperature of the coolant within the coolant jacket is below a first predetermined
  • FIG. 1 is a partially sectioned elevation showing a currently used conventional water circulation type system discussed in the opening paragraphs of the instant disclosure
  • FIG. 2 is a schematic side sectional elevation of a prior art arrangement also discussed briefly in the earlier part of the specification;
  • FIG. 3 shows in schematic layout form, another of the prior art arrangements previously discussed
  • FIG. 4 shows in partial section yet another of the previously discussed prior art arrangements
  • FIG. 5 is a graph showing, in terms of engine torque and engine/vehicle speed, the various load zones encounted by an automotive vehicle;
  • FIG. 6 is a graph showing, in terms of pressure and temperature, the change which occurs in the coolant boiling point with change in pressure
  • FIG. 7 shows in schematic block form the system which characterizes the present invention
  • FIG. 8 shows in sectional elevation an engine system which embodies the present invention
  • FIG. 9 shows in sectional elevation the construction of a pressure differential responsive switch which may be utilized in the arrangement shown in FIG. 8;
  • FIGS. 10-16 are flow charts showing the steps which characterize the control operations of an embodiment of the present invention.
  • FIG. 6 graphically shows, in terms of engine torque and engine speed, the various load "zones" which are encountered by an automotive vehicle engine.
  • the curve F denotes full throttle torque characteristics
  • trace L denotes the resistance encountered when a vehicle is running on a level surface
  • zones I, II and III denote respectively what shal be referred to as “urban cruising”, “high speed cruising” and “high load operation” (such as hillclimbing, towing etc.).
  • a suitable coolant temperature for zone I is approximately 110° C. while 100°-98° C. (for example) for zones II and III.
  • the high temperature during "urban cruising" of course promotes improved fuel economy while the lower temperatures promote improved charging efficiency while simultaneously removing sufficient heat from the engine and associated structure to obviate engine knocking and/or engine damage in the other zones.
  • FIG. 7 shows in schematic block diagram form a systematic representation of the present invention.
  • the present invention is depicted as including three major sections. Viz., a cooling circuit (A), a reservoir (B) and a control means (C).
  • A cooling circuit
  • B reservoir
  • C control means
  • cooling circuit includes (a) a coolant jacket formed about portions of the engine which are subject to high heat flux and in which coolant is permitted to boil, (b) a condensor in which the vapor produced by the boiling of the coolant in the coolant jacket is condensed back to its liquid state (this element although not shown includes a cooling fan or like device for assisting heat exchange between the condensor and the ambient atmosphere), (c) a condensate collection tank which is disposed at the bottom of the radiator and arranged to collect the liquid coolant from the radiator, and (d) a coolant return pump which returns the liquid coolant from the collection tank back to the coolant jacket.
  • a coolant jacket formed about portions of the engine which are subject to high heat flux and in which coolant is permitted to boil
  • a condensor in which the vapor produced by the boiling of the coolant in the coolant jacket is condensed back to its liquid state (this element although not shown includes a cooling fan or like device for assisting heat exchange between the condensor and the ambient atmosphere
  • the cooling circuit (A) is arranged to fluidly communicate with the reservoir (B) through what shall be termed “valve and conduit means” (D) which is arranged to be controlled by the control means (C).
  • control means (C) includes circuitry for (i) executing "normal condition control” and (ii) detecting and controlling the system in the event that an "abnormal condition” such as the inclusion of too much or too little coolant within the system or the occurrence within the cooling circuit of a sub-atmospheric pressure of a magnitude which is sufficiently low to lower the coolant boiling point to the degree of causing engine overcooling or worse, damage (crushing) to the cooling circuit itself.
  • an "abnormal condition” such as the inclusion of too much or too little coolant within the system or the occurrence within the cooling circuit of a sub-atmospheric pressure of a magnitude which is sufficiently low to lower the coolant boiling point to the degree of causing engine overcooling or worse, damage (crushing) to the cooling circuit itself.
  • First and second level sensors (E) & “F) which sense the level of coolant in the coolant jacket, and the condensate collection tank, respectively, along with temperature and pressure sensor means (“G” & “H”) the latter of which detects the presence of an abnormally low pressure (relative to the ambient atmospheric pressure) within the system; supply data to the control means (C) which in turn in response to same outputs the appropriate control to the condensor (b), return pump (d) and the valve and conduit means (D).
  • E First and second level sensors
  • G temperature and pressure sensor means
  • the control means when the engine is cold (viz., the temperature of the engine coolant is below 75° C.--by way of example) and the pressure within the system less than atmospheric, the control means provides fluid communication between the cooling circuit (A) and the reservoir (B) and permits the cooling circuit to be completely filled with liquid coolant. This prevents the entry of contaminating atmospheric air.
  • the control means (C) energizes the coolant return pump (d) while simultaneously conditioning the valve and conduit means (D) so that the pump (d) inducts coolant from the reservoir and pumps same into the cooling circuit to overfill same and thus purge out any non-condensible matter which might have found its way into the system.
  • the control means (C) conditions the valve and conduit means (D) to cut off fluid communication therethrough and place the cooling circuit in a "closed" state.
  • control means operates the condensor according to a normal operation schedule so as to induce a rate of condensation therein which is suited to the given engine/vehicle operation.
  • This monitoring takes the form of (to determined the presence of excess coolant within the system) firstly adjusting the level of coolant in the coolant jacket (a) to the appropriate level and then, in the event that the level of coolant is above that of the second level senor ("F"), energizing the coolant return pump (d) to move the excess coolant from the condensate collection tank (c) to the coolant jacket (a) unil the level of coolant in the condensate coolection tank (c) falls to that of the second level sensor ("F").
  • the time required for this transfer is taken as a measure of how much excess coolant is retained within the cooling circuit.
  • the time required in excess of a predetermined period for the coolant return pump (d) to establish the appropriate level of coolant in the coolant jacket can be taken as an indication that either an insufficient amount of coolant has been retained within the cooling circuit or alternatively that coolant has been lost from the system due to leakages or the like.
  • placing the system in a closed state with insufficient coolant retained therein can prevent the structure of the engine such as the cylinder head exhaust ports and valves etc., which are subject to high heat flux, from being immersed in sufficient coolant to ensure that localized dry-outs (which lead to the formation of hot spots which subsequently tend to perpetuate the dry-out) and subsequent thermal damage to the engine do not occur.
  • FIG. 8 shows an engine system incorporating a first embodiment of the present invention.
  • an internal combustion engine 100 includes a cylinder block 106 on which a cylinder head 104 is detachably secured.
  • the cylinder head 104 and cylinder block 106 include suitable cavities which define a coolant jacket 120 about the heated portions of the cylinder head and block.
  • a vapor manifold 121 and vapor transfer conduit 122 provide fluid communication between a vapor outlet port 124 formed in the cylinder head 104 and a radiator or heat exchanger (viz., condensor) 126.
  • the interior of the relatively small diameter conduits which define the actual heat exchanging surface of the radiator 126 are maintained essentially empty of liquid coolant (dry) during normal engine operation so as to maximize the surface area available for condensing coolant vapor (via heat exchange with the ambient atmosphere) and that the cooling circuit (viz., the circuit which in the illustrated embodiment includes the coolant jacket, radiator and conduiting interconnecting same) is hermetically closed when the engine is warmed-up and running.
  • a mesh screen or like separator (not shown) can be disposed in the vapor discharge port 124 of the cylinder head so as to minimize the transfer of liquid coolant which tends to forth during boiling, to the radiator 126.
  • cylinder head/manifold arrangements such as disclosed in U.S. Pat. No. 4,499,866 issued on Feb. 19, 1985 in the name of Hirano and U.S. patent application Ser. No. 642,369 filed in June 25, 1984 in the name of Hirano et al, can be employed if desired.
  • a electrically driven fan 127 Located suitably adjacent the radiator 126 is a electrically driven fan 127.
  • a small collection reservoir or lower tank 128 as it will be referred to hereinafter.
  • a level sensor 130 Disposed in the lower tank 128 is a level sensor 130 which is adapted to output a signal indicative of the level of liquid coolant in the lower tank 128 falling below same. Viz., being below a level selected to be lower than the lower ends of the tubing which consitute the heat exchanging portion of the radiator.
  • a return conduit 132 Leading from the lower tank 128 to the cylinder block 120 is a return conduit 132. As shown, a "three-way" type electromagnetic valve 134 and a relatively small capacity return pump 136 are disposed in this conduit. The valve 134 is located upstream of the pump 136. The return conduit 132 is arranged to communicate with the lowermost portion of the coolant jacket 120.
  • a (first) level sensor 140 is disposed as shown. It will be noted that this sensor is arranged at a level higher than that of the combustion chambers, exhaust ports and valves (structure subject to high heat flux) so as to ensure that they are securely immersed in coolant and thus attenuate any engine knocking and the like which might otherwise occur due to the formation of localized zones of abnormally high temperature of "hot spots”.
  • a temperature sensor 144 Located below the level sensor 140 so as to be immersed in the liquid coolant is a temperature sensor 144.
  • a coolant reservoir 146 is located beside the engine proper as shown.
  • the reservoir is advantageously disposed at a relatively high position with respect to the engine so that a gravity feed effect is obtained. It should be noted however, that if the engine layout so demands, the reservoir can be located in positions other than the illustrated one and that the present invention is not limited to same.
  • An air permeable cap 148 is used to close the reservoir 146 in a manner that atmospheric pressure continuously prevails therein.
  • the reservoir 146 fluidly communicates with the "three-way" valve 134 via a supply conduit 149 and with the engine coolant jacket 120 via a displacement/discharge conduit 150 and an ON/OFF type electromagnetic valve 152. This valve is closed when energized. As shown, the conduit 150 communicates with the lower tank 128 at a location essentially level with the second level sensor 130.
  • the vapor manifold 121 includes a riser-like portion 162 in which a "purge" port 163 is formed.
  • a cap 164 hermetically closes the riser 162.
  • Port 163, as shown, communicates with the reservoir 164 via an overflow conduit 168.
  • a normally closed electromagnetic valve 170 is disposed in the overflow conduit 168. This valve is opened when energized.
  • a sensor 172 which is responsive to the pressure differential between the pressure prevailing in the cooling circuit and that of the ambient atmosphere is arranged to communicate with the riser 162.
  • the above mentioned level sensors 130 & 140 may be of any suitable type such as float/reed switch types.
  • control circuit 180 includes therein a microprocessor including input and output interfaces I/O a CPU, a RAM and a ROM. Suitable control programs are set in the ROM and are used to control the operation of the valves 134, 152 & 170, pump 136 and fan 127 in response to the various data supplied thereto.
  • a load sensor 182 and an engine speed sensor 184 are arranged to supply data signals to control circuit 180.
  • the load sensor may take the form of a throttle position switch which is triggered upon the engine throttle valve being opened beyond a predetermined degree; alternatively the output of an air flow meter of an induction vacuum sensor may be used.
  • the engine speed signal may be derived from the engine distributor, a crankshaft rotational speed sensor or the like.
  • FIG. 9 shows an example of the pressure differential responsive sensor 172 used in the illustrated embodiment.
  • a casing 90 is divided into an atmospheric chamber 91 and a pressure chamber 92 by a flexible diaphragm 93.
  • a suitable contact 94 is mounted in the center of the diaphragm 93 and arranged to provide electrical connection between a pair of electrodes 95 which are arrange to protruded into the atmospheric chamber 91 of the device.
  • a spring 96 having a preselected bias is disposed in the pressure chamber 92 and arranged to bias the diaphragm 93 in a direction which brings the contact 94 into engagement with the electrodes 95.
  • the spring 96 is selected so that when a pressure which is lower than atmospheric by a predetermined amount prevails within the cooling circuit the diaphram 93 deflects in a manner which brings the contact 94 out of engagement with the electrodes 95 and thus opens the circuit. This is used as an indication that a negative pressure of a predetermined magnitude has developed within the system and it is either possible or necessary (depending on the instant mode of engine operation) to the place the cooling circuit in an "open" condition.
  • a filter element 97 is disposed as shown to prevent the entry of dust and the like into the atmospheric chamber 91.
  • the cooling system Prior to initial use the cooling system is completely filled with coolant (for example water or a mixture of water and antifreeze or the like) and the cap 164 securely set in place to seal the system.
  • coolant for example water or a mixture of water and antifreeze or the like
  • a suitable quantity of additional coolant is also placed in the reservoir 146.
  • the coolant e.g. water
  • the coolant in the reservoir will tend to absorb atmospheric air and each time the system is filled with coolant to as to obviate any negative pressures and exclude the entry of air, a little non-condensible matter will tend to find its way into the system.
  • a non-condensible matter purge operation is carried out upon start-up of the engine, given that the engine temperature is blow a predetermined value (45° C. for example) a non-condensible matter purge operation is carried out.
  • the purge operation is effected by pumping coolant into the system for a predetermined period of time. As the system should be essentially full of coolant at this time, the excess coolant thus introduced positively displaces any air or the like the might have collected.
  • FIG. 10 shows the characterizing steps executed by the microprocessor (control circuit 180) during what shall be termed a "system control routine".
  • the system is initialized (step 1000).
  • step 1001 it is determined in step 1001 whether the temperature of the engine coolant is greater than 45° C. If the outcome of this enquiry shows that the coolant is still cold (viz., below 45° C.) then the program proceeds to step 1002 wherein a "non-condensible matter purge routine" is effected. If the temperature of the coolant is above 45° C., then the engine is deemed to be "hot” and the program by-passes the purge routine and effects what shall be termed a "hot start". In the event that the purge routine is carried out, the system is considered as undergoing a "cold start".
  • the program enters a "coolant displacement routine" wherein the coolant which fills the radiator and coolant jacket is displaced under the influence of the pressure which develops within the system when the coolant has been heated sufficiently.
  • the program goes on to enter a normal "control routine" (step 1004).
  • shut-down control routine (see FIG. 11) is executed.
  • This routine includes an interrupt (step 2001) which breaks into the program which is currently being run and proceeds to at step 2002 enter a routine which continues to control the system after the engine is stopped and the ignition switch is opened, until the system enters a state whereat switching from closed to open states is possible without violent discharge of coolant.
  • FIG. 12 shows a flow chart depicting the steps which characterize the control executed during the "non-condensible matter purge routine".
  • the program proceeds in step 3001 to condition the valves of the system so that valve I (152) is energized so as to assume a closed state, valve II (134) is de-energized so as to establish flow path A (viz., fluid communication between the reservoir 146 and the coolant jacket 120) and valve III (170) is energized so as to assume an open condition and thus establish fluid communication between the riser of the vapor manifold and the reservoir 146 via conduit 168.
  • step 3002 energization of the pump 136 for a predetermined period of time (10 seconds-1 minute by way of example only) in step 3002, inducts coolant from the reservoir 146 and forces same into the coolant jacket 120 via conduit 132.
  • this brief energization of the pump 134 forces sufficient additional coolant into the system as to ensure that any traces of non-condensible matter (air or the like) are purged out of the system and forced to flow along with the excess coolant via valve III (170) back to reservoir 146 via overflow conduit 168.
  • step 3003 the program determines if a timer arrangement which will be referred as being a first timer or timer (1), included in the microprocessor (a software timer by way of example) and which is triggered by the operation of the pump in step 3002, has counted up to the predetermined period of time or not. If the answer to the enquiry carried out in this step is negative, then the program recycles as shown until a positive result is obtained. At step 3004 the operation of the pump is stopped and the purge routine terminates.
  • a timer arrangement which will be referred as being a first timer or timer (1), included in the microprocessor (a software timer by way of example) and which is triggered by the operation of the pump in step 3002, has counted up to the predetermined period of time or not. If the answer to the enquiry carried out in this step is negative, then the program recycles as shown until a positive result is obtained.
  • step 3004 the operation of the pump is stopped and the purge routine terminates.
  • the first step (4001) of this control process takes the form of setting three electromagnetic valves of the valve and conduit arrangement as shown. Viz., a situation wherein valve I is energized to assume an open condition, valve II energized to establish flow path B between the lower tank 128 and the coolant jacket 120 while the valve III is de-energized to assume a closed condition.
  • step 4002 an enquiry is carried out to determine if the level of coolant in the lower tank 128 is lower than the "second" level sensor 130 disposed therein. If the outcome of this enquiry indicates that the level of coolant has not yet fallen thereto, then at step 4003 the operation of fan 127 is prevented and subsequently valve I opened (step 4004) so as to permit the discharge of some of the excess coolant out to the reservoir 146. On the other hand, if the level of the coolant in the lower tank 128 has fallen to that of the second level sensor 130 then the program goes to step 4005 wherein it is determined if the pressure in the cooling circuit is lower than atmospheric pressure.
  • valve I (152) is energized to close same and cut-off fluid communication between the coolant circuit and the reservoir 146. This step prevents the possibility that as the level of coolant in the lower tank is below that of sensor 130, coolant vapor may be vented to the atmosphere through conduit 150.
  • the target temperature (viz., the temperature most appropriate for the instant mode of engine operation) is determined.
  • This step can be executed by setting a two-dimensional table of the nature shown in FIG. 5 into the ROM of the microprocessor and using the data inputs from the engine load and speed sensors 182 and 184 to determine via table look-up the appropriate temperature for the instant operational conditions.
  • a suitable program which calculates the appropriate or target temperature in view of the magnitude of said inputs can be used.
  • the instant coolant temperature is compared with the target value derived in step 4007.
  • the fan control operations contained in steps 4009 and 4010 are by-passed.
  • the fan 127 is energized to increase the rate heat exchange between the ambient atmosphere and the radiator surface and thus the rate of condensation within the radiator 126. This of course tends to lower the pressure within the system and thus the temperature at which the coolant in the coolant jacket 120 boils.
  • the fan is stopped to reduce the rate of condensation and thus induce an increase in the boiling point of the coolant.
  • step 4011 it is determined if the level of coolant within the coolant jacket is lower than the first level sensor 140. In the event of a negative result (that is the level is above the first sensor) then the program recycles to step 4002. On the other hand, in the vent of a positive result the fan is stopped (step 4012).
  • step 4013 an enquiry is made as to whether valve I is open or not. If the outcome of this enquiry reveals that the valve is still open, then the program proceeds to step 4014 wherein it is determined if the level of coolant in the coolant jacket is below level sensor 140 or not. If the result of this enquiry is positive pump 136 is energized at step 4015 while in the event of a negative result the operation of the pump is stopped at step 4016. Susequently, at step 4017 the level of the coolant in the lower tank is sampled. If the level is above level sensor 130 the program recycles to step 4014 while in the event that the level is in fact lower than level sensor 130 then at step 4018 valve I is closed. After this the program returns.
  • the steps executed in this control routine are such as to permit the coolant be driven out of the cooling circuit under the influence of the increasing vapor pressure therein while simultanously maintaining the level of coolant within the coolant jacket 120 at that of the "first" level sensor 140.
  • the displacement of coolant tends to be such that the level of coolant in the coolant jacket falls to that of the level sensor 140 before the level in the radiator falls to that of level sensor 130.
  • step 13A are repeatedly executed (via recycling between steps 4001 and 4011) so that the coolant in the coolant jacket is moved to the radiator in the form of vapor and valve I repeatedly opened and closed (steps 4003 and 4006) to permit the coolant transfered from the coolant jacket to the radiator to be removed little by little.
  • steps 4007-4010 the engine is controlled (steps 4007-4010) in a manner to maintain the appropriate target temperature and/or open the circuit and allow the induction of coolant into the cooling circuit should a negative pressure develop and thus obviate any possiblity of "overcooling" during the displacement mode.
  • overcool control and the displacement of coolant are controlled by the same steps (steps 4003, 4004) depending on the pressure prevailing in the system.
  • the present invention provides for the amount of coolant entrapped within the system to be periodically monitored and if an inappropriate amount of coolant is determined to be within the system, then steps are taken to correct the situation.
  • FIGS. 14A and 14B An example of a "monitoring" program which can be run at predetermined intervals is shown in FIGS. 14A and 14B.
  • the most appropriate temperature for the instant set of operational conditions (Viz., Target Temp) is determined at step 5001 whereafter an enquiry as to the instant coolant temperature is carried out by sampling the output of temperature sensor 144.
  • the temperature of the coolant is accordingly adjusted by selectively energizing or stopping the energizing of fan 127 in steps 5003 and 5004 in a manner similar to that set forth in connection with steps 4008-4010 in the excess coolant displacement routine (FIG. 13A).
  • the output of the level sensor 140 is sampled to determine if the level of coolant in the coolant jacket is above or below the same.
  • a software timer (by way of example) which shall be referred to as a "second" timer or timer (2) is read and a determination made as to how long the level of coolant within the coolant jacket has remained below that of level sensor 140. This measurement may be taken from the time for which the pump is operated in order to restore the level of coolant jacket (that is to say, return the coolant which is continuously being boiled and transmitted in the form of coolant vapor to the radiator 126).
  • step 5007 it is assumed that insufficient coolant is retained within the cooling circuit and valve II (134) is de-energized to establish flow path A between the reservoir and the coolant jacket.
  • pump 136 is energized to pump additional coolant into the system and thus bring the amount of coolant within the cooling circuit up to that required.
  • step 5009 the program flows to step 5009 wherein valve II is energized to establish flow path B (viz establish fluid communication between the lower tank 128 and the coolant jacket 120).
  • step 5010 timer (2) is cleared.
  • step 5012 If the answer is NO then the program bypasses step 5012 and proceeds directly to step 5013 wherein a third software timer or timer (3) is cleared. Subsequent to step 5013 the operation of the pump is stopped in step 5014. However, in the event that the answer to the enquiry made at step 5011 is YES and the temperature is sensed as being higher than the aforementioned level--which indicates the possible presence of an excessive amount of coolant within the cooling circuit--then at step 5012 it is determined if the level of coolant in the lower tank is in fact above level sensor 130. If the level is below said sensor, then the program flows to step 5013.
  • step 5015 it is determined if the third timer (timer (3)) has counted up to a predetermined level (in this embodiment the equivalent of 10 seconds). If the third timer has clocked up a time of greater than 10 seconds then the program flows to steps 5016 to 5018 (FIG. 14B) wherein the pump and fan are stopped and the third timer cleared. Following step 5018 the program flows to step 1003 (shown in FIG. 10) wherein the excess coolant displacement routine (shown in detail in FIGS. 13A and 13B) are re-implemented). This of course removes the excess coolant from the system which induced the undesireably high temperature (detected in step 5011 of the retained coolant check/control routine.
  • step 5015 if the time sampled at step 5015 is less than 10 seconds, then the program flows across and down to step 5008 wherein the operation of pump 136 is stopped.
  • FIG. 15 shows a flow chart which depicts the control exercised during the above mentioned mode of operation.
  • the output of the temperature sensor 144 is sampled and a determination made as to whether the coolant temperature is above 97° C. or not. In the event that the temperature is above said level the program flows to RETURN and thus terminates. However, if the temperature is determined to be lower than 97° C. then at step 6002 the output of the pressure sensor 172 is sampled and a determination made as to whether the pressure prevailing in the cooling circuit is below the predetermined level at which diaphragm 93 flexes and brings contact contact 94 out of engagement with electrodes 95. If a negative pressure of the just mentioned level has not yet developed then the program flows to RETURN whereat the instant run terminates.
  • step 6003 the program goes to step 6003 whereat the valves of the valve and conduiting arrangement are conditioned as shown. Viz., valve I is de-energized to assume an open condition and thus "open” the cooling circuit and valve II is energized to establish flow path B. Valve III (170) is maintained de-energized (closed).
  • step 6004 the output of level sensor 140 is sampled to determine if the level of coolant within the coolant jacket is lower than that desired. In the event that the coolant level is below that of level sensor 140 then as step 6005 pump 136 is energized. On the other hand, if a sufficient amount of coolant is present in the coolant jacket 120 then the operation of the pump is stopped. These steps of course ensure that the desired level of coolant is maintained within the coolant jacket despite the system being temporarily placed in an "open" condition.
  • step 6007 the pressure prevailing within the system is again sampled and in the event that the pressure remains below the lower acceptable limit then the program recycles to step 6004.
  • step 6008 the level of coolant in the lower tank 128 is determined by sampling the output of sensor 130. In the event that the level of coolant is still above that of sensor 130 then the program recycles back to step 6004.
  • step 6009 valve I is energized to close and thus seal the system.
  • FIG. 16 shows in flow chart form the control exercised during what shall be termed the shut-down mode of operation. As shown in FIG. 11 this program is implemented after an interrupt is carried out to break into the program being currently run in the CPU of the microprocessor in response to the stoppage of the engine. This may be determined by sampling the output of the engine speed sensor 184.
  • the first step of the shut down control involves terminating all current fan and valve I ON/OFF controls.
  • a fourth timer is cleared ready for timing the operations of the shut-down.
  • the status of the engine ignition switch is determined. That is to say, to determine between an accidental stalling of the engine and an intentional stoppage of the engine. If the switch is ON, then it is assumed that the engine has not been deliberately stopped and the program flows to step 7004 wherein the ON/OFF control of the fan and valve I terminated in step 7001 is restored.
  • step 7005 the program flows to step 7005 wherein the output of temperature sensor 144 is sampled. If the temperature of the coolant is found to be less than 75° C. then the program immediately flows to step 7014 wherein the supply of electrical power to the entire system is terminated. However, if the temperature of the coolant is still above 75° C. then at step 7006 a command is issued which closes or maintains closed valve I. Subsequently, at step 7007 the time for which fan 127 has been maintained operative after the positive determination that the engine has been deliberately stopped, as determined by timer (4).
  • step 7009 the operation thereof is terminated (step 7009) and the program flows to step 7010 wherein the level of coolant within the coolant jacket is determined by sampling the output of level sensor 140. As shown in steps 7011 and 7012, the desired level is maintained to ensure that the highly heated structure of the engine is securely immersed in sufficiently coolant as to allow for the thermal inertia resulting from the heat capacity of the cylinder head, cylinder block etc.
  • step 7014 the pressure within the system is sampled. If still above that at which the pressure differential sensor 172 is triggered then the program recycles to permit further cooling to take place. However, in the event that the pressure within the cooling circuit has fallen below that at which the pressure differential responsive sensor 172 switches, then the program flows to step 7014 whereat shut-down is completed and the system conditioned so that coolant is permitted to be induced into the cooling circuit under the mild negative pressure which has developed therein and to continue to be inducted as the temperature of the system continues to fall and the vapor continues to condense.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
US06/704,269 1984-02-23 1985-02-22 Cooling system for automotive engine Expired - Fee Related US4577594A (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP3299484A JPS60175727A (ja) 1984-02-23 1984-02-23 エンジンの沸騰冷却制御装置
JP59-32994 1984-02-23
JP59-100157 1984-05-18
JP10015584A JPS60243320A (ja) 1984-05-18 1984-05-18 内燃機関の沸騰冷却装置
JP10015784A JPS60243318A (ja) 1984-05-18 1984-05-18 内燃機関の沸騰冷却装置
JP59-100155 1984-05-18

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Cited By (7)

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US4694784A (en) * 1985-04-24 1987-09-22 Nissan Motor Co., Ltd. Cooling system for automotive engine or the like
USRE34139E (en) * 1988-10-21 1992-12-08 Caterpillar Inc. Engine piston assembly and forged piston member therefor having a cooling recess
US5435485A (en) * 1992-07-24 1995-07-25 Gas Research Institute Automatic purge system for gas engine heat pump
US20020189555A1 (en) * 2001-06-13 2002-12-19 Aisan Kogyo Kabushiki Kaisha Engine cooling system
US20030079698A1 (en) * 2001-10-31 2003-05-01 Visteon Global Technologies, Inc. Method of engine cooling
WO2008091027A3 (en) * 2007-01-25 2008-10-23 Toyota Motor Co Ltd Cooling apparatus
US10371469B2 (en) * 2011-12-12 2019-08-06 Gigaphoton Inc. Device for controlling temperature of cooling water

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JPS6183437A (ja) * 1984-09-29 1986-04-28 Nissan Motor Co Ltd 内燃機関の沸騰冷却装置

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US4352342A (en) * 1978-11-30 1982-10-05 Autoipari Kutato Intezet Automatic ventilation apparatus for liquid systems with forced flow
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4694784A (en) * 1985-04-24 1987-09-22 Nissan Motor Co., Ltd. Cooling system for automotive engine or the like
USRE34139E (en) * 1988-10-21 1992-12-08 Caterpillar Inc. Engine piston assembly and forged piston member therefor having a cooling recess
US5435485A (en) * 1992-07-24 1995-07-25 Gas Research Institute Automatic purge system for gas engine heat pump
US20020189555A1 (en) * 2001-06-13 2002-12-19 Aisan Kogyo Kabushiki Kaisha Engine cooling system
US6679201B2 (en) * 2001-06-13 2004-01-20 Aisan Kogyo Kabushiki Kaisha Engine cooling system
US20030079698A1 (en) * 2001-10-31 2003-05-01 Visteon Global Technologies, Inc. Method of engine cooling
US6758172B2 (en) * 2001-10-31 2004-07-06 Visteon Global Technologies, Inc. Method of engine cooling
WO2008091027A3 (en) * 2007-01-25 2008-10-23 Toyota Motor Co Ltd Cooling apparatus
US20100071637A1 (en) * 2007-01-25 2010-03-25 Toyota Jidosha Kabushiki Kaisha Cooling apparatus
CN101589212B (zh) * 2007-01-25 2011-10-05 丰田自动车株式会社 冷却设备
US8281753B2 (en) 2007-01-25 2012-10-09 Toyota Jidosha Kabushiki Kaisha Cooling apparatus
US10371469B2 (en) * 2011-12-12 2019-08-06 Gigaphoton Inc. Device for controlling temperature of cooling water

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EP0153694B1 (de) 1990-01-17
DE3575451D1 (de) 1990-02-22
EP0153694A2 (de) 1985-09-04
EP0153694A3 (en) 1986-11-20

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